Photocatalytic reduction of carbon dioxide using Fe2TiO5 nanosheets

Abstract

A method of reducing carbon dioxide (CO 2 ) including contacting a catalyst and the CO 2 and irradiating the catalyst and the CO 2 with visible light. Upon irradiating the CO 2 is reduced to a conversion product. The catalyst includes Fe 2 TiO 5 in the form of nanosheets. The nanosheets have an average width of 200 nanometers (nm) to 800 nm and form a hierarchical structure.

The invention claimed is: 
     
       1. A method of reducing carbon dioxide, comprising:
 contacting a catalyst and the carbon dioxide; and 
 irradiating the catalyst and the carbon dioxide with visible light, 
 wherein on the irradiating the carbon dioxide is reduced to a conversion product, 
 wherein the catalyst comprises Fe 2 TiO 5 , 
 wherein particles of the Fe 2 TiO 5  are in a form of nanosheets, 
 wherein the nanosheets have an average width of 200-800 nm, and 
 wherein the nanosheets form a hierarchical structure of two or more of the nanosheets stacked on top of one another. 
 
     
     
       2. The method of  claim 1 , wherein the nanosheets are crystalline. 
     
     
       3. The method of  claim 1 , wherein the nanosheets have an interplanar distance of 0.3-0.4 nanometers (nm). 
     
     
       4. The method of  claim 1 , wherein the nanosheets have an average length of 1-3 micrometers (μm). 
     
     
       5. The method of  claim 1 , wherein the catalyst comprises 45-55 wt. % Fe, 25-35 wt. % O, and 15-25 wt. % Ti, based on a total weight of the catalyst. 
     
     
       6. The method of  claim 1 , wherein the catalyst absorbs light from 200-550 nm. 
     
     
       7. The method of  claim 1 , wherein the catalyst has a peak light absorbance from 375-425 nm. 
     
     
       8. The method of  claim 1 , wherein the catalyst has a band gap of 1.9-2.2 electron volts (eV). 
     
     
       9. The method of  claim 1 , wherein the catalyst does not comprise Fe 2 O 3  or TiO 2 . 
     
     
       10. The method of  claim 1 , wherein the carbon dioxide is in a gaseous state. 
     
     
       11. The method of  claim 1 , wherein the carbon dioxide is in an aqueous solution. 
     
     
       12. The method of  claim 1 , wherein the conversion product is at least one selected from the group consisting of methanol and dimethyl ether. 
     
     
       13. The method of  claim 1 , wherein the irradiating is for 1 min to 10 hours. 
     
     
       14. The method of  claim 1 , wherein the visible light has a wavelength of 400-700 nm, and a power of 10-100 watts (W). 
     
     
       15. The method of  claim 1 , wherein the conversion product is methanol, and a yield of the methanol is 120-160 μmol per gram of the catalyst after irradiating for 4 hours. 
     
     
       16. The method of  claim 1 , wherein the conversion product is dimethyl ether, and a yield of the dimethyl ether of 40-60 micromoles per gram (μmol) of the catalyst after irradiating for 4 hours. 
     
     
       17. The method of  claim 1 , wherein the catalyst has a higher conversion to the conversion product than TiO 2  under the same conditions. 
     
     
       18. The method of  claim 1 , wherein the Fe 2 TiO 5  is made by a method comprising:
 mixing an iron salt in a solvent to form a first mixture; 
 adding titanium isopropoxide to the first mixture to form a second mixture; 
 heating the second mixture in an autoclave at a temperature of 150-200° C. for 1-24 hours to form a suspension; 
 separating a precipitate from the suspension; and 
 calcining the precipitate at a temperature of 400-800° C. for 1-24 hours to form the catalyst.